Resistor Model

Type Name: r

The resistor model consists of process-related device data that allow the resistance to be calculated from geometric information and to be corrected for temperature. The parameters (multiple names are aliases) available are:

Resistor Model Parameters
name	parameter	units	default	example
m	parallel multiplier	-	1.0	1.2
tc1, tc, tc1r	first order temperature coeff.	$\Omega$/C	0.0	-
tc2, tc2r	second order temperature coeff.	$\Omega$/C2	0.0	-
rsh	sheet resistance	$\Omega$/$\Box$	-	50
defl, l	default length	M	0	2e-6
defw, w	default width	M	0	2e-6
dl, dlr	length reduction due to etching	M	0	1e-7
narrow, dw	narrowing due to side etching	M	0	1e-7
tnom, tref	parameter measurement temperature	C	25	50
temp	default instance temperature	C	25	50
kf	flicker noise coefficient		0
af	flicker noise exponent of current		2
ef	flicker noise exponent of frequency		1
wf	flicker noise exponent of width		1
lf	flicker noise exponent of length		1
noise	noise conductance multiplier		1

The sheet resistance is used with the etch reduction parameters and l and w from the resistor element line to determine the nominal resistance by the formula

R = rsh ^. (l - dl)/(w - narrow).

The parameters defw and defl are used to supply default values for element w and l if not specified on the device line. A fatal error is produced if the resistance can't be determined from given parameters.

After the nominal resistance is calculated, it is adjusted for temperature by the formula:

R(temp) = R(tnom) ^. (1 + tc1 ^. (temp- tnom) + tc2 ^. (temp- tnom)² )

Finally, the resistance is divided by the parallel multiplier (m) value.

The flicker noise capability can be used in noise analysis. This requires that kf, l, and w be specified. To use, the instance line must reference a model, but also can have a resistance specified which will override model calculation of resistance.

Flicker noise model:

Noise = (KF ^. I^AF)/(Leff^LF ^. Weff^WF ^. f^EF)

Param	Description	Units
Noise	Noise spectrum density	A2 Hz
I	Current	A
Leff	Eff length (L-DL)	M
Weff	Eff width (W-DW)	M
f	Frequency	Hz
Param	Description	Default, Range
KF	Flicker noise coefficient	0, > = 0
AF	Exponent of current	2, > 0
LF	Exp. of eff. length	1, > 0
WF	Exp. of eff. width	1, > 0
EF	Exp. of frequency	1, > 0

The noise parameter will multiply the conductance used in the noise equations. It provides a default which is overridden by the instance parameter of the same name. This can be used to model empirical excess noise, or to remove the devices from noise analysis by setting the parameter to zero.